1. Field of the Invention
The field of this invention comprises aircraft and more particularly vertical take-off and land vehicles and ground effect machines.
2. Description of the Prior Art
Vertical take-off and land vehicles vary from helicopters, providing low power economic hovering but slow, inefficient horizontal propulsion, to turbojet lifting engines, providing short duration, inefficient hovering but high speed horizontal propulsion. None of these vehicles offer the combination of low power, economic hovering and economic horizontal propulsion at low speeds in the range of up to about seventy to one hundred miles per hour.
Ground effect machines comprise various classes and designs, the most pertinent of which is the air cushion vehicle. Air cushion vehicles ride on a cushion of compressed air generated and maintained in a space between the vehicle and the ground. The basic design includes a plenum chamber on the bottom that is open towards the ground. In operation, a large volume of air is blown into the chamber and forced against the ground causing the vehicle to lift. The air expanding in the chamber results in a loss in energy with the result being a very inefficient operation. Various methods of increasing efficiency including providing annular jets, nozzles, ducts, ejectors and rubber skirts have been tested but have met with little success. The design parameters of the air cushion vehicles in the prior art are greatly limited. The optimum design is round and the amount of available lift depends on surface area. A commercialized air cushion vehicle of the approximate size of the conventional, family automobile has yet to be widely commercialized. None of these air cushion vehicles are capable of operating at altitudes of more than a couple of feet off the ground, and all of them suffer from a lack of maneuverability and stability making them impractical for commercial use.